Re: what is time?
According to latest versions of science neither time nor space is absolute. For every observer its different. Time is relative to the velocity, that is speed of light. & we know that gravitational force can effect light. Bcos as we now know gravitational force is caused by the particles called graviton and they r of spin 2. They contain no mass and hence the long range and for the same reason this force is the weakest of all. And it effects the light as we now know the light is both, particles or waves, just how u would like to see (i dont wanna go in the depth of particle theory) The effect of gravitation on light has been proven near large bodies such as our sun during eclipse etc.
Now assume the gravitational force is so strong that light cannot escape the event horizon, the time which is relative to the velocity of light will become zero for the observer who is inside the event horizon.
So to answer ur question of time is relative to what i would say relative to the velocity of light. & there r only two ways to slow it down, travel that fast, or stop the light.
